Number of permutations of 1..n with displacements restricted to {-4,-3,0,1,2}.

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =13a(5) =26a(6) =48a(7) =95a(8) =205a(9) =456a(10) =974a(11) =2024a(12) =4225a(13) =8930a(14) =18977a(15) =40199a(16) =84815a(17) =178867a(18) =377753a(19) =798542a(20) =1687806a(21) =3565554a(22) =7531030a(23) =15908857a(24) =33611337a(25) =71013181a(26) =150026395a(27) =316943191a(28) =669573901a(29) =1414567938